Magnetic recording medium

Abstract

Provided is a particulate magnetic recording medium for high-density recording having a low error rate and good running durability. The magnetic recording medium comprises a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic powder and a binder in this order on at least one surface of a nonmagnetic support. Said nonmagnetic support comprises a clay mineral coated with an organic material, and said ferromagnetic powder is a ferromagnetic hexagonal ferrite powder having an average plate diameter ranging from 5 to 40 nm or a ferromagnetic metal powder having an average major axis length ranging from 20 to 100 nm.

1. A magnetic recording medium comprising a nonmagnetic layer comprising a nonmagnetic powder and a binder and a magnetic layer comprising a ferromagnetic powder and a binder in this order on at least one surface of a nonmagnetic support, wherein
 said nonmagnetic support comprises a clay mineral coated with an organic material, wherein said clay mineral coated with an organic material is a compound obtained by subjecting a layered silicate compound to the action of organic onium ions, and  
 said ferromagnetic powder is a ferromagnetic hexagonal ferrite powder having an average plate diameter ranging from 5 to 40 nm or a ferromagnetic metal powder having an average major axis length ranging from 20 to 100 nm.  
 
     
     
       2. The magnetic recording medium according to  claim 1 , wherein said ferromagnetic powder is a ferromagnetic hexagonal ferrite powder having an average plate diameter ranging from 10 to 38 nm. 
     
     
       3. The magnetic recording medium according to  claim 1 , wherein said ferromagnetic powder is a ferromagnetic hexagonal ferrite powder having an average plate diameter ranging from 15 to 36 nm. 
     
     
       4. The magnetic recording medium according to  claim 1 , wherein said ferromagnetic powder is a ferromagnetic metal powder having an average major axis length ranging from 30 to 90 nm. 
     
     
       5. The magnetic recording medium according to  claim 1 , wherein said ferromagnetic powder is a ferromagnetic metal powder having an average major axis length ranging from 40 to 80 nm. 
     
     
       6. The magnetic recording medium according to  claim 1 , wherein said layered silicate compound is at least one member selected from the group consisting of smectite clay, swelling mica, and swelling vermiculite. 
     
     
       7. The magnetic recording medium according to  claim 1 , wherein said layered silicate compound is montmorillonite, beidellite, nontronite, saponite, iron saponite, hectorite, sorconite, stibnite, bentonite, substitution products thereof, derivatives thereof, or mixtures thereof. 
     
     
       8. The magnetic recording medium according to  claim 1 , wherein said layered silicate compound is Li-type tenorite, Na-type tenorite, Li-type tetrasilicon mica, and Na-type tetrasilicon mica, substitution products thereof, derivatives thereof, or mixtures thereof. 
     
     
       9. A method of reproduction with a magnetoresistive (MR) head, wherein the reproduction is conducted on the magnetic recording medium according to  claim 1 .